linux-kernel - Re: [PATCH 14/21] x86/intel_rdt/cqm: Add mon

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Date:   Thu, 6 Jul 2017 14:48:15 -0700 (PDT)
From:   Shivappa Vikas <vikas.shivappa@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
cc:     Vikas Shivappa <vikas.shivappa@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, hpa@...or.com, peterz@...radead.org,
        ravi.v.shankar@...el.com, vikas.shivappa@...el.com,
        tony.luck@...el.com, fenghua.yu@...el.com, andi.kleen@...el.com
Subject: Re: [PATCH 14/21] x86/intel_rdt/cqm: Add mon_data



On Sun, 2 Jul 2017, Thomas Gleixner wrote:

> On Mon, 26 Jun 2017, Vikas Shivappa wrote:
>
>> Add a mon_data directory for the root rdtgroup and all other rdtgroups.
>> The directory holds all of the monitored data for all domains and events
>> of all resources being monitored.
>
> Again. This does two things at once. Move the existing code to a new file
> and add the monitoring stuff. Please split it apart.

Will fix.

>
>> +static bool __mon_event_count(u32 rmid, struct rmid_read *rr)
>> +{
>> +	u64 tval;
>> +
>> +	tval = __rmid_read(rmid, rr->evtid);
>> +	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
>> +		rr->val = tval;
>> +		return false;
>> +	}
>> +	switch (rr->evtid) {
>> +	case QOS_L3_OCCUP_EVENT_ID:
>> +		rr->val += tval;
>> +		return true;
>> +	default:
>> +		return false;
>
> I have no idea what that return code means.

false for the invalid event id and all errors for __rmid_read. (IOW all errors 
for __mon_event-read)

>
>> +	}
>> +}
>> +
>> +void mon_event_count(void *info)
>
> Some explanation why this is a void pointer and how that function is called
> (I assume it's via IPI) would be appreciated.
>
>> +{
>> +	struct rdtgroup *rdtgrp, *entry;
>> +	struct rmid_read *rr = info;
>> +	struct list_head *llist;
>
>  *head;
>
>> +
>> +	rdtgrp = rr->rgrp;
>> +
>> +	if (!__mon_event_count(rdtgrp->rmid, rr))
>> +		return;
>> +
>> +	/*
>> +	 * For Ctrl groups read data from child monitor groups.
>> +	 */
>> +	llist = &rdtgrp->crdtgrp_list;
>> +
>> +	if (rdtgrp->type == RDTCTRL_GROUP) {
>> +		list_for_each_entry(entry, llist, crdtgrp_list) {
>> +			if (!__mon_event_count(entry->rmid, rr))
>> +				return;
>> +		}
>> +	}
>> +}
>
>> +static int get_rdt_resourceid(struct rdt_resource *r)
>> +{
>> +	if (r > (rdt_resources_all + RDT_NUM_RESOURCES - 1) ||
>> +	    r < rdt_resources_all ||
>> +	    ((r - rdt_resources_all) % sizeof(struct rdt_resource)))
>> +		return -EINVAL;
>
> If that ever happens, then you have other problems than a wrong pointer.
>
>> +
>> +	return ((r - rdt_resources_all) / sizeof(struct rdt_resource));
>
> Moo. Can't you simply put an index field into struct rdt_resource,
> intialize it with the resource ID and use that?

Ok will fix all above,

thanks,
Vikas

>
> Thanks,
>
> 	tglx
>